Control circuit for telephone extension signals and the like



May 29, 19 5- .1. H. WHEELOCK 2,377,059

CONTROL CIRCUIT FOR TELEPHONE EXTENSION SIGNALS AND THE LIKE Filed June 14. 1943 2 Shets-Sheet l IHVENTOIR JOHN H. WH EELOC K WW Z 26 ATTOPNEY y 1945- J. H. WHEELOCK 2,377,059

CONTROL CIRCUIT FOR TELEPHONE EXTENSION SIGNALS AND THE LIKE Fil ed June 14, 1943 2 Sheets-Sheet 2 IINENTOR JOHN H. WHEELOCK Patented May 29, 1945 UNI TED -STATES PAT-EN T "OFFICE 2,s77;05'9 CONTRO'ILJCIRCUIT FOR riiilizi iibmz 'E'XTEN'SIGN SIGNALS AND THE LIKE John H. Whelock, Fitzwillia'm, fl 'as sigfior-to Signal Engineering & Mwnpfqeturi g 'Cm npany New York, N. Y., a corporation of Massachusetts Apimeetien n, 1942., semi Ne.'490,m'4

-1 2 Cleims. (019133-81) Them-resent invention relates 120 an *hhp 'eved coht'ro'l y-ar hehgemenc for employing te'l'efihori'e ringing current {to lock a'h'electrical circuit ina iven "s'ig'tidflihgstatt'us, iihtil rel-e'asedby trefi'sie'iit telefihdnefielkiflg current obtained through the removere:wee ventiehhl receiver from itsEhehk, o'r un t fl 'releafsed 'al-tltoniatieahy after a predten mined labsebftirhein the event thatthe receiver is net removed. 7

When a telepheneextensibn relay is e'fiergized by ri g-in'g diiriefit, it 'lOSs and 'COffiPlts a, air cui't frdm a suitable power sburce to 'the"ext'e'i1- si'oh signal, eueh "as a 'louii 'sdundi 'g ho'rn, 'ong, or lamp, an'd in 'ifiost instances it is desirailiile to have the extension signal 'remai'h ciih'tii udlisly ehe'rgize'd until the person called answers 'thetelephohe. To this end, j'telephoheextehfi idn relays have 'he'retbfbre been p'fdv'ided 'With venous types of meehei r'fic'all latehing devices which serve to lock "up the relay armature in respo se to the first applfcatidh of ringing 011*ehtahdjis0 maintain the Circ'iiit 'o'f the eict'efil's'ibh signal Heretdfere, sha -mechanical lejt'ehing iievie'es have been 'r'la'se d by '9, lillk'ilill al 'o'p'er'ati'o'h Sb "afs t0 deenergize the ek'ter'fsio'n signal when the person called 'ahswels filie teleph'o'he; consequently the ext'ehsien s i'gn'al Will remain energi'zea the event that the person ahewerih'g neglects he perform the unl'htdhifig dp eratib'n, 0i" does 'ri'Ot anea'lly bring jh'bbut the release of the telephdhe.

nstrument. 'Fufithehntsre, the circuit previaes' eehe fdr egtiteiiratieailyreleasing the telephone extehsie reray in the-ever'it that the "receiver is not lifted after the 'lapsee'f 'aflpredetermfriii e rio d d f tirrre measured frb'm the re'c'eipt 6f the iifitiejl 'ihjpulse of iifi'giiig'bifrient to energize the si'ehhl. The ai-bbv "and ether advantageous fe tu'i'e'sbf *the invention will hereinhrt'er-mere funy eppai' frdm the following description cohhidere'd i *qdnneetien with the ee'eemphnymg 'di'awihgs, mjwhieh I mg hfilliistia'tes the 'cOnditi0n of the 'dirdtiit withtheieeeiyer fully lifted for thetrensmission o'f 'yoide'ttrrlits; v v

Fig. 5 illlitra'tes meafhs for auteinaitichlly releasing the extension relay 'Iipon iepe'e of e predetefhfiheq ti-ine interval, with the *reeeiver ehn u'rilifted. i

Fig. 6 is a schematic view similar to Fig. 1, i1- lustlfatinga modifiation df the diiiiit errafige riient.

Fig. "8 is a plan view Of "the contacts shown in Fig; '1. 7

Referring fitst to Fig. 1, the invention "shown f'er fiiiriidses 'bf illustration es be'ihg employed in eehhectib'h with the bnvefitibnel apparatus uiially ihisteiled withetelephehe subseriberss'et, in'clhding a bell B tr'ainsrrfitter TR and receiver R. I heincdiiiih'g Iifie to the subsdrilgiers set is indicated-by the eehquevere 11-1 hear-:2, with these c'bhdeeters se'r'vih t9 cc'ihvey either Yi'fig'iiig cuireht ft'o operate the he); B er 'tal'kihg eurr'ejht 1:6 aha "fioin the receiver R and transmitter TR respectively;

tact 5. An extension signal S, such as a loud sounding bell or horn, or if desired a lamp, is adapted to be operated from a separate source of electrical ener y, such as commercial power mains 6, through engagement of the contact 5 by the relay-operated contact 4.

Therefore, with the arrangement described thus far, telephone ringing current coming in over L-I and L-Z will cause ringing of the bell B, as well as operation of the signal S through pulling in of the relay I to close the contacts 4 and 5 as indicated in Fig. 2.

In order to hold, in the relay I after the first impulse of ringing current and thereby maintain the extension signal S in signalling status, the relay I provides a latch I. This latch I is pivoted at 8 and provides a notch 9 adapted to fit under the end of relay armature 3 when the latter is moved from the position of Fig. l to the position of Fig. 2. The latch 1 provides a trip arm I which, when the latch is in the position of Fig. 1, tends to turn the latch about its pivot 8 as soon as the free end of the armature 3 enters the notch 9 in response to pulling in of the armature 3 by the winding 2. Therefore, whenever the extension signal relay I is energized by ringing current, the armature 3 will be automatically locked in its attracted position to maintain the signal S continuously energized from the power mains 6 through closed contacts 4 and 5, and thereby call attention to the fact that an incoming call should be answered at the telephone subscribers set, as represented by the receiver R and transmitter TR.

In order to automatically unlatch the relay 2 in response to removal of the receiver R to answer the call, the relay I further provides a trip coil I I located beneath the trip arm II]. The coil has a magnetic plunger I2 associated therewith, with the lower end of the plunger resting against a stop I3 so that a portion of the plunger is outside of the coil. Therefore, energization of the trip coil II will tend to draw the plunger I2 upwardly to engage the trip arm i0 and so exert a turning force on the latch I tending to move the notch 9 away from the end of the relay armature 3.

One terminal of the trip coil II is connected to the line conductor L--I in series with the winding I4 of the receiver R, while the other terminal thereof is connected to a contact I5, normally spaced from the hook IB of the telephone receiver R. The hook is movable and is illustrated diagrammatically as being held down away from the trip coil contact I5 by the weight of the receiver R. The hook has also associated therewith contacts I"! and I8 respectively connected to the receiver winding I4 and to a winding I9 of the transmitter TR. The several contacts I5, I1 and I8 are different distances from the hook I6, and since the hook itself is connected to the other line conductor L2, upward movement of the hook upon removal of the receiver R will bring about a sequence of operations, resulting in silencing the extension signal S in advance of carrying on a conversation at the subscribers set.

Assuming that ringing current has caused looking up of the relay I to energize the extension signal S, as shown in Fig. 2, it is evident that signal S will be maintained in its signalling status as long as the receiver R holds down the hook I6. However, when anyone starts to answer the incoming call at the subscribers set by lifting the receiver R, the resulting upward movement of the hook I6 almost immediately engages the contact I5 which, as hereafter described, is yieldable with respect to the hook. When this occurs, the trip coil II is connected across the line conductors L-I and L-Z in series with the receiver winding I4 and the resulting flow of transient talking current energizes the trip coil II. This results in pulling up the plunger I2 to engage the trip arm II) and thereby turn the latch into the position oi Fig. 3. Since the relay winding 2 is then deenergized, the armature 3 is free to fall and thereby cause disconnection of the extension si nal S from the mains 6 as the contacts 4 and 5 are disengaged.

Completion of the upward movement of the hook I6 causes the contacts I8 and H to be engaged in that order, thereby connecting first the transmitter winding l9 and then the receiver winding I4 across the line conductors for the transmission of voice currents. It is to be noted that with the hook it engaging both contacts I5 and H, the relay trip coil I I will be short-circuited and therefore will have no disturbing efiect on the transmission of voice currents to and from the subscribers set. When, upon completion of the telephone conversation, the receiver R is replaced on its hook IIS, all of the circuits will be restored to the condition of Fig. l, with the telephone extension relay I in non-signalling status and with the trip coil II entirely removed from the circuit of the subscribers set, so that the entire arrangement is in readiness to signal an incoming call in response to the next succeeding impulse of ringing current.

As previously pointed out, the invention also provides means for releasing the telephone extension relay in the event that the receiver is not lifted after the lapse of a predetermined period of time, measured from the receipt of the initial impulse ringing current to operate the signals. Such an arrangement is shown in Fig. 5, in which elements of the circuit common to Fig. l are designated by like reference characters, inasmuch as these elements function in the same manner as described with reference to Fig. 1,.

should the receiver be lifted while the time interval is still running.

Referring to Fig. 5, it will be noted that the terminal of the coil I I, which is connected to the hook contact I5, is also connected to a yieldable contact 20 that is normally separated from a contact 2I connected to the line conductor L2. LA thermal element 2, indicated as being of the bimetal type, is associated with the contact 20, so that when the element 22 is at ordinary room temperature, an insulating button 22a of the element is just bearing on the contact 20.

A heating coil 23 for the element 20 has one terminal connected to one power main 6 in common with the relay contact 4, while the other terminal thereof is connected to an extra contact 24 of the relay I adjacent to the extension signal contact 5. Therefore, closure of the contacts I and 5 to operate the extension signal S, as indicated in dotted lines in Fig. 5, will also result in connecting the heating coil 23 across the mains 6.

Assuming that an impulse ringing current has locked the relay I in signalling status and that no one lifts the receiver at the subscribers set in order to answer the call, the heat generated by the coil 23 will cause the expanding thermal element 22 to swing laterally and slowly move the contact 20 in the direction of the contact 2I. This movement continues until, after the lapse of a predetermined time interval governed by the design of the element, the contact will engage the contact 2i, thereby connecting the "trip coil II to the line conductor L-Z, with the resulting flow of transient talking current serving to un latch the extension relay I. In other words, closure o'fcontacts '20 and -2I has the same result as upward movement of the hook I6 to engage the contact I5, as previously described with reference to Fig. 3. I

As soon as the relay I drops back to disengage the relay contact 4 from the contact 24, the resulting cooling and contraction of the thermal element 22 will permit separation of the contacts 20 and 21, thereby disconnecting the trip coil II from line conductor L2 and restoring the entire circuit to its normal non-signalling status. Obviously, other types of time delay devices can be employed to cause automatic release of the extension relay after the lapse of a predetermined interval following the receipt of an impulse of ringing current.

Referring now to Fig. 6, there is shown a modified circuit arrangement whereby the trip coil I I is adapted to be only momentarily energized by talking current independently of the receiver winding I4, the trip coil bein thereafter entirely shunted out of the telephone circuit until the extension relay is again locked'up. In this arrangement, a pair of spaced contacts 25 are connected across the terminals of the trip coil II and when the relay is in non-signalling status, these contacts are bridged by a plate 26 carried by, although insulated from, the latch 1., Furthermore, in the modified arrangement, one terminal of the trip coil II is connected directly to the line conductor L-I beyond the receiver winding I4.

Assuming that therelay 'I has been locked up in response to ringing current, the resulting turning movement of the latch 7 into the position of Fig. 2 will unbridge "the contacts 25, thereby establishing a direct circuit from the line conductor L--I through the trip coil I I to the hook contact I5. Therefore, lifting of the receiver R to the position of Fig. 3 will result in the passage of transient talking current directly through the trip coil II, independently of the receiver winding I4. However, the resulting unlatching of the armature 3 will quickly again bridge the contacts 25, so that by the time the receiver hook I6 has reached the position of Fig. 4, in engagement with contacts I! and I8, the trip coil will have been tact pairs I 6a-'I'5, rec-rs and 1611-11 in the order'named.

As shown in Fig. 8, the trip coil contacts Ilia,

and I5 are mounted on aninsulating block 30, displaced from a similar insulatingblock 3| which carries both pairs of instrument contacts lib-I1 and IBc-I8. Obviously, other contact arrangements can be employed within the base of a standard subscriber's set for accomplishing the results described above, the particular showing of Figs. 7 and 8 being merely an illustrative emboditional telephone receiver from its hook at the subscribers set being called.

I claim: I

l. .A control circuit comprising in combination, a source of telephone ringing current, a separate source of electrical energy, an-electrical sigentirely shunted out of the talking circuit, as

indicated in Fig. 6.

Referring now to Figs. 7 and 8, there is shown in detail the mounting of the hook controlled contacts of Fig. 1 within the base of a telephone subscribers set, the outlines of the instrument and base being indicated in dot and dash lines.

In Fig. 7, the hook I 6, shown diagrammatically in Fig. 1 is in the form of a spring pressed plunger 2'! which is held down in the position shown by the weight of the combined receiver R and transmitter TR, as .indicated. The lower end of the plunger 21 carries a pair of spaced contacting actuating plates 28 and 29 of insulating material, which plates bear upon the contact fingers I6a, I6b and IE0, corresponding collectively to the movable hook I6 in Fig. l. The several contacts I5, I! and I8 are represented by the correspondingly designated short contact fingers, and the sequence of operation is such that upward movement of the hook I6 upon removal of the receiver will result in successive engagement of the connalling device, means for employing telephone ringing current to lock said electrical device in continuous signalling status and means automatically responsive to transient telephone talking current for placing said device on a non-signalling status. I

2. A-control circuit comprising iii-combination, a source of telephone ringing current, a separate source of electrical energy, an electrical signaling device, means for employing telephone ringing current to lock said electricaldevice-in continuous signalling status and means automatically responsive to lifting of a telephone receiver for placing said device on a non-signalling status.

3. A control circuit comprising in combination, a sourceof telephone ringing current, a separate source of electrical energy; an electrical signaling device, means for employing telephone ringing current to lock said electrical device in continuous signalling status and means automatically responsive to the lapse of a predetermined time interval following the response to ringing current, for placing said device on a non-signaling status.

4. A control circuit comprising in combination, a source of telephone ringing current, a separate source of electrical energy, an electrical'signalling device, means for employing telephone ringing current to lock said electrical device in continuous signalling status and means automatically responsive to lifting of a telephone receiver for placing said device on a non-signalling status, said circuit also providing means for placing said device on a non-signalling status, in the event that said receiver is not lifted within a predetermined period following the response of said device to ringing current.

5. A'control circuit comprising in combination, a source of telephone ringing current, a separate source of electrical energy, a telephone extension signal normally in non-signalling status, means for employing telephone ringing current to lock said signal in signalling status, with respect to said separate source, and means responsive to the flow of transient telephone talking current to unlock said signal.

6. A control circuit comprising in combination,

for employing telephone ringing current'to lock said signal in signalling status, with respect to said separate source, and means responsive to removal of a conventional telephone receiver from its hook to unlock said signal.

7. A control circuit comprising in combination, a source of telephone ringing current, a separate source of electrical energy, a telephone extension signal normally in non-signalling status, means for employing telephone ringing current to lock said signal in signalling status, through its connection to said separate source, and means responslve to the manual operation of a conventional telephone instrument for the purpose of answering a call, to restore said signal to its nonsignalling status by disconnection from said separate source.

8. A control circuit comprising in combination, a source of telephone ringing current, a separate source of electrical energy, a telephone extension signal normally in non-signalling status, means for employing telephone ringing current to lock said signal in signalling status through its connection to said separate source and means responsive to lifting of a telephone receiver for unlocking said signal, said circuit also providing means for restoring said signal to its non-signalling status, in the event that said receiver is not lifted Within a predetermined period following the response of said signal to ringing current.

9. A control circuit comprising in combination, a source of telephone ringing current, a. separate source of electrical energy, a telephone extension relay for normally maintaining an associated signal in non-signalling status, said relay being responsive to ringing current to energize said signal from said separate source, means for locking said relay in signalling status, and means responsive to the flow of transient telephone talking current to unlock said relay and restore said signal to non-signalling status.

10. A control circuit comprising in combination,

a source of telephone ringing current, a separate source of elctrical energy, an electrically operated signal, a telephone extension relay for normally maintaining said signal in non-signaling status, said relay being responsive to ringing current to energize said signal from said separate source and lock itself in signaling status, and means comprising relatively movable contacts incorporated in the base of a conventional telephone instrument for unlocking said relay in response to the removal of the receiver of said instrument.

11. A control circuit comprising in combination, a source of telephone ringing current, a separate source of elctrical energy, an electrically operated signal, a telephone extension relay for normally maintaining said signal in non-signaling status, said relay being responsive to ringing current to energize said signal from said separate source and lock itself in signaling status, and means comprising relatively movable contacts incorporated in the base of a conventional telephone instrumentfor utilizing transient telephone talking current to unlock said relay, as soon as the receiver of said instrument is lifted.

12. A control circuit compirsing in' combination, a source of telephone ringing current, a separate source of electrical energy, an electrically operated signal, a telephone extension relay for normally maintaining said signal in nonsignaling status, said relay being responsive to ringing current to energize said signal from said separate source and lock itself in signaling status, and means comprising relatively movable contacts incorporated in the base of a conventional telephone instrument for utilizing transient telephone talking current to unlock said relay, as soon as the receiver of said instrument is lifted, with said unlocking means being thereafter maintained out of the talking circuit of said instrument.

JOHN H. WHEELOCK. 

